We demonstrate a hybrid solar cell which was made by blending nanocrystalline ZnO (nc-ZnO) and conjugated polymer regioregular poly(3-hexylthiophene) (P3HT) as the active layer of the solar cell. It can be seen that the efficiency of this new type of solar cells obviously varied as the size and morphology of ZnO nanostructures. The short-circuit photocurrent, fill factor, and power conversion efficiency were enhanced while the smaller nc-ZnO was utilized in such a device.